Myth: Partial DID is the same as OSDD

One clinician writes OSDD in the notes. Another talks about partial DID.¹² Then an online discussion treats the words as interchangeable, and suddenly nobody seems to be describing quite the same thing.

The confusion starts with the manuals themselves. DSM-5-TR has no partial DID category.² ICD-11 does, alongside DID, other specified dissociative disorder, and unspecified dissociative disorder.¹ So the same presentation can end up with a different name depending on which manual the clinician is using.

I put the codes here for quick reference. Each one links straight to the relevant WHO ICD-11 entry.¹

ICD-11 diagnosis	Reference code
Dissociative identity disorder	6B64
Partial dissociative identity disorder	6B65
Other specified dissociative disorder	6B6Y
Unspecified dissociative disorder	6B6Z

What does “partial” mean?

In ICD-11, the difference to pay attention to is executive control. With DID, at least two identity states recurrently take control. With partial DID, one dominant state is usually the one handling work, errands, conversations, and most of everyday life. Other states intrude, but they take control infrequently and irregularly. A particularly distressing or emotional situation may be when that happens.³⁴²

The word “partial” causes trouble because it sounds like a severity rating. Here, it describes the pattern of identity states taking control. Someone can meet the partial DID criteria and still have their daily life seriously disrupted.⁴²

Why I got stuck on the labels

When I first saw “partial DID,” I read partial as less severe. I know clinicians don't mean it that way, but the word gets there first. “OSDD” created a similar problem for me. Other specified sounds like a leftover category, something that exists because the real diagnosis didn't quite fit.

Carolyn Spring writes that people with OSDD can feel “unheard and unseen” when the conversation puts too much weight on dissociative parts.⁵ That line helped me understand why a label can feel dismissive even when the clinician is using it carefully.

The presentations don't always line up with the ladder I had in my head. In a video about partial DID, Mike Lloyd discusses a presentation with total blackout episodes. A separate discussion of covert and subtle DID gives a very different picture. The contrast shows why visible switching and apparent severity are poor shortcuts.

The labels also gave my OCD something to do. I started checking which category I belonged in, rereading criteria, and trying to make every experience fit neatly into one box. That kind of checking didn't make the answer clearer. It just made the uncertainty louder. A diagnosis is useful when it helps a clinician describe a pattern and plan care; it isn't a puzzle I can solve by inspecting myself all day.

Personally, spectrum language makes more sense to me than a ladder from mild to severe. I think DID, partial DID, and OSDD should be collapsed into one diagnosis, with the person's actual presentation recorded as part of the clinical picture. Frequency, amnesia, control, elaboration, and how visible the symptoms are can vary in more than one direction. Dell's proposed Complex Dissociative Disorder I and II model moves toward that kind of description. He also argued that older DDNOS-1 research may have combined covert DID with genuinely subtler cases.⁶ The treatment could then stay shared across the presentations, with the same kind of adjustments clinicians make for any person's particular symptoms, risks, and needs.

Mike Lloyd's “buckets” image helped me understand why partial DID felt like its own slot in ICD-11 rather than another name for OSDD.⁷

OSDD covers more than one pattern

A clinician using DSM-5-TR may land on OSDD when dissociative symptoms are causing serious problems but the full criteria for another named disorder do not fit. They also record why.²

One OSDD presentation involves chronic identity disruption without all the features required for DID. That can resemble partial DID, which explains why the labels are often paired online. OSDD also covers other situations, including identity disturbance after prolonged coercive persuasion, short-lived dissociative reactions to stress, and dissociative trance.²

If a record only says OSDD, the name leaves part of the story out.² Which symptoms did the clinician see? What kept the presentation from fitting DID? It isn't helpful to reduce OSDD and partial DID to the same label when they describe different criteria.

Dell goes further than that. In his discussion of the older DDNOS-1 category, he points out that DDNOS-1a was common in one SCID-D database, then questions how much that result depended on the interview's threshold for calling identity states “sufficiently distinct.”⁶ He argues that many cases called DDNOS-1a may have been false-negative DID cases, especially covert DID that did not present clearly during the assessment. In plain terms, he thought this form of OSDD was being used too often for cases that belonged under DID.

This is close to why I think DID, partial DID, and the DID-like forms of OSDD should be brought together under one diagnosis. People bring up OSDD-1a and OSDD-1b a lot, but they aren't current DSM-5-TR or ICD-11 diagnoses. They came from older examples and are also used as community shorthand for different OSDD presentations. Read more about OSDD-1a and OSDD-1b.

When the diagnosis stays unspecified

Sometimes a clinician has enough information to recognise a dissociative disorder but not enough to choose a more specific diagnosis. ICD-11 uses unspecified dissociative disorder for that situation. The code does not mean partial DID, OSDD-1, or “probably DID.”⁸

If two labels show up, ask which manual each clinician used and what criteria they applied. The reasoning behind the label matters more than making OSDD and 6B65 line up word for word.⁹¹⁰

Footnotes10

Footnotes

1. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Dissociative disorders. Dissociative disorders overview. ICD-11 grouping and structure for dissociative disorder categories. ↩ ↩² ↩³

2. International Society for the Study of Trauma and Dissociation. (2026). Fact Sheet IV – What are the Dissociative Disorders? DID and OSDD clinical definitions. ISSTD overview differentiating DID, OSDD, and related dissociative categories. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

3. World Health Organization. (2024). Clinical descriptions and diagnostic requirements for ICD-11 mental, behavioural and neurodevelopmental disorders. pp. 382-383, Essential (required) features and Additional clinical features. ICD-11 DID requirements, including recurrent executive control by at least two identity states, amnesia, impairment, exclusions, and the normality threshold. ↩

4. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Partial dissociative identity disorder. Code 6B65. ICD-11 code for partial DID, in which one dominant identity state usually handles daily life while non-dominant states intrude and take control infrequently. ↩ ↩²

5. Spring, C. (n.d.). DID or OSDD: Does it matter? The importance of validating OSDD. Lived-experience and clinical discussion of OSDD, DID, parts, amnesia, and the risk of treating OSDD as an afterthought. ↩

6. Dell, P. F. (2009). The long struggle to diagnose multiple personality disorder (MPD): Partial MPD. In P. F. Dell & J. A. O'Neil (Eds.), Dissociation and the dissociative disorders: DSM-V and beyond (pp. 403-428). Routledge. Chapter 25, pp. 403-428; DDNOS-1, covert DID, subtle DID, and proposed Complex Dissociative Disorder I and II. Dell's proposed distinction between covert DID and genuinely subtler presentations, and his proposed Complex Dissociative Disorder I and II model. This is a proposed framework, not current DSM or ICD criteria. ↩ ↩²

7. Lloyd, M. (2025). Partial DID or OSDD: Classifying and diagnosing types of dissociation. 03:21, 06:42. Video explanation of DID and OSDD boundaries and partial DID as an intermediate formulation. ↩

8. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Unspecified dissociative disorder. Code 6B6Z. ICD-11 unspecified code used when a specific diagnosis cannot be established. ↩

9. International Society for the Study of Trauma and Dissociation. (2011). Guidelines for treating dissociative identity disorder in adults, third revision. Journal of Trauma & Dissociation, 12(2), 115-187. pp. 128-130. Differential diagnosis and common sources of diagnostic confusion. ↩

10. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Dissociative identity disorder. Code 6B64. ICD-11 coding and diagnostic criteria family for DID. ↩